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From: robert_dewar@my-dejanews.com
Subject: Re: Calculating SQRT in ADA
Date: 1999/03/25
Message-ID: <7dei54$dv2$1@nnrp1.dejanews.com>#1/1
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 <19990324201959.00800.00000708@ngol04.aol.com>
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Date: 1999-03-25T00:00:00+00:00
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In article <19990324201959.00800.00000708@ngol04.aol.com>,
  johnherro@aol.com (John Herro) wrote:
> Robert Dewar wrote:
> >>   while ...
> >>        abs(Guess*Guess/X - 1.0) > 3.0*Dummy'Epsilon
loop
> > Why the epsilon test, this iteration will terminate to
> > exact equality in any reasonable floating-point model
...
>
> I don't know if the Open Ada 83 compiler has a
"reasonable" floating-point
> model, but I do know that if I test for exact equality,
instantiate with type
> Float, and compute Sqrt(2.0) with that compiler, the
program goes into an
> infinite loop.  I think that in general, you can't
guarantee that Guess*Guess
> will ever exactly equal X.


Of course not!

The proper way for testing for convergence is to see if
the new guess is the same as the last guess!

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